The present invention is directed to catheters adapted for passage through the accessory channel of an endoscope into a duct or passageway within the gastrointestinal system of the body. Although not limited in its applicability and scope, the invention has particular applicability to procedures which involve the advancement of the catheter to positions within the biliary tract and especially to the practice of Endoscopic Retrograde Cholangiopancreatography.
A number of procedures have evolved in recent years using instruments intended to be inserted through an endoscope in various positions within the gastrointestinal system for the purpose of diagnosis and for therapeutic procedures, including the insertion of stents, devices for the extraction of stones from the biliary duct, the removal of polyps and the extraction of tissue for biopsy purposes.
One diagnostic technique which has come into use is Endoscopic Retrograde Cholangiopancreatography (ERCP) which is described in copending application Ser. No. 07/880,842, filed May 11, 1992. The ERCP technique is an endoscopic technique which involves the placement of a side-viewing instrument within the descending duodenum. The procedure eliminates the need for invasive surgical procedures for identifying biliary stones and other obstructions of the biliary and pancreatic ducts. As background of the invention, the ERCP technique exemplified the problems and difficulties which the present invention addresses.
Utilizing this technique, the Papilla of Vater and common biliary duct are cannulated, contrast medium injected and pancreatic ducts and the hepatobiliary tree visualized radiographically or examined with a duodeno fiberscope. Skilled medical practitioners can visualize approximately 90-95% of the biliary and pancreatic ducts using this technique.
ERCP is typically performed on an X-ray table. During the procedure, the patient""s oropharynx is anesthetized with topical lidocaine, and the patient is sedated intravenously with diazepam. Atropine and glucagon are given intravenously to relax the duodenal muscles.
The ERCP procedure has heretofore typically been performed by the endoscopic introduction of a single lumen catheter into the pancreatic and common biliary ducts of a patient. Such ERCP catheters have typically been constructed from Teflon(copyright). At times, a spring wire guide may be placed in the lumen of the catheter to assist in cannulation of the ducts. A stylet, used to stiffen the catheter, must first be removed prior to spring wire guide insertion. The introduction of the spring wire guide eliminates the ability to inject contrast medium or makes it highly cumbersome.
To summarize the procedure, an ERCP catheter is initially inserted through the endoscope and into the biliary or pancreatic ducts. If difficulty is encountered or if the operator so desires, a spring wire guide is threaded into the catheter to assist in the cannulation. After the catheter is inserted into the duct and threaded over the spring wire guide, the spring wire guide is removed. A radio-opaque contrast medium is then injected through the single lumen of the catheter in order to identify obstructions such as bile stones. Once located and identified, such stones can then be eliminated or destroyed by methods such as mechanical lithotripsy utilizing a device such as an Olympus BML-10/20 Mechanical Lithotriptor.
This method of performing ERCP has several disadvantages. Most notably, it relies upon the use of a single lumen catheter which is threaded over the spring wire guide or pushed by a stylet and then, upon the removal of the stylet or spring wire guide is then used for infusing radio-opaque contrast medium or dye into the biliary and pancreatic ducts. Unfortunately, the process of withdrawing the stylet or spring wire guide in order to clear the single lumen for contrast medium or dye infusion frequently repositions the catheter. Thus, when the radio-opaque or contrast medium is injected into the catheter, the catheter is often improperly positioned for proper fluoroscopy or X-ray visualization. Moreover, this method presents the further problem of having to repeatedly remove the stylet or an approximately six foot long spring wire guide, maintain its cleanliness and then reinsert it into the catheter. In addition, the dye is sticky and reintroduction of the guide wire is made difficult due to the frictional resistance offered by it. Finally, single lumen catheters frequently experience the problem of back-flow in which the radio-opaque dye is squirted back out the side port of the catheter and onto the administering medical professional.
The above problems often result in the need to repeat the procedure and a time consuming exercise of trial and error. Multiple attempts at properly positioning the catheter and spring wire guide are often necessary. Increased amounts of tracer dye associated with multiple injections increase the risk of pancreatitis. Because the ERCP procedure is performed under sedation, the additional time required for proper catheter positioning tends to increase the risk to the patient. Furthermore, because of the considerable expense of maintaining a procedure room, the use of single lumen ERCP catheters can add considerably to the expense of the procedure. Accordingly, practice of ERCP procedures has heretofore been limited to only the most skilled endoscopists.
The invention has particular applicability in the performing of ERCP procedures, other diagnostic and surgical procedures performed within the biliary system, as well as other parts of the gastrointestinal system in general, by the use in such procedures of catheters having at least two lumens, and preferably three or four lumens. The multi-lumen catheter assemblies of the invention are specially designed to be inserted into a duct or body passage through the accessory channel of an endoscopic instrument. A catheter assembly for use in carrying out the invention comprises, in its broadest aspects, a catheter body of substantially cylindrical shape and substantially uniform diameter having a plurality of independent lumens extending lengthwise thereof. At least two lumens exit at the distal tip of the catheter body with each exit port facing generally distally along the passage being explored axially and forwardly. The catheters of the present invention are sized to be passed through the accessory port of a conventional endoscopic instrument. The catheters have a combined length sufficient to extend the length of the standard accessory channel and into the more remote portions of the duct or passage and further have a proximal section extending proximally of the endoscope channel for a sufficient distance to allow for manipulation of the catheter by the user into the most extreme position. In the exemplary case of the biliary system, the invention allows for substantially complete exploration and visualization without the need to remove the spring wire guide. Follow-up procedures, such as stent placement, tissue sampling, use of a papillotome/sphincterotome or the like are accomplished through a lumen of the catheter already placed and may be accompanied by periodic dye injection and visualization without removal of the catheter. For certain of these procedures, the wire guide is preferably left in place, as will be noted in the explanation which follows. A further advantageous embodiment of the invention involves a multi-lumen catheter with a reduced diameter distal tip portion on which a dilatation balloon is secured. In a related embodiment, a reduced diameter distal end portion serves as a platform for a stent.
The use of multi-lumen catheters for procedures such as described above offers many advantages over the prior art practice of using single-lumen catheters. As noted above, one important advantage is the facility for injection of contrast medium so as to attain complete visualization of a system of passages, such as the biliary tract, without the need to remove the spring wire guide. When one recognizes that a catheter for use in ERCP procedures must be approximately 200 cm in length and the spring wire guide must be an additional 200 cm or so in length, the very act of removal of the spring wire guide to allow for injection of contrast medium through a single-lumen catheter can be seen to be both awkward and time consuming. Since the spring wire guide is needed again for repositioning the catheter, its extreme length and resilient nature makes it very difficult to avoid loss of sterility when it is temporarily removed from the catheter. Furthermore, when the spring wire guide is reinserted after injection of the contrast medium through the single lumen, it has been found that because the contrast medium tends to be sticky, the resistance offered within the lumen impedes reintroduction. This condition is aggravated due to the relatively small diameter and the length of the lumen through which the spring wire guide must be passed. Since the catheters can be properly placed much more easily with less trial and error, the provision of separate lumens for dye injection and guide wire placement has been found to dramatically reduce the use of tracer dye. In addition, the provision of a separate lumen for guide wire placement eliminates the risk that air will enter the biliary tract as may occur when a single lumen is used for dye and guide wire. Still further, it is highly desirable to have further lumens within the catheter to allow for other procedures, such as the introduction and removal of stents, the use of instruments, such as papillotomes, biopsy cutters, stone extractors, forceps, knives and the like. Accordingly, it is an important objective of the invention to provide a multi-lumen catheter of small enough diameter to pass through the accessory channel of the endoscopic instrument having the following characteristics: to provide for additional lumens sized to permit the aforementioned procedures within the limited cross-section available; to retain the requisite flexibility so as to facilitate passage to a final position within an extended tortuous-passageway; and to maintain the patency of the lumens without bunching up or kinking as the catheter is advanced over the spring wire guide and into a final position.
One aspect of the invention is the provision of a catheter constructed from a blend of resins producing a catheter body having peak stress of at least 8000 psi and a torqueability of at least 0.3 inch ounce at body temperature, wherein torqueability is measured as resistance to twisting through 360xc2x0 with one end of the catheter fixed. An important feature of the present invention involves the treatment of at least the distal end section of the catheter with a hydrophilic coating. The hydrophilic coating of the present invention provides a highly lubricated surface which is activated by the presence of moisture. In the case of a biliary catheter, the biliary fluids activate the coating as it enters the biliary passage of the patient. The hydrophilic coating serves the further function of softening the catheter body so as to increase its suppleness and kink resistance and lubricity. Further, the softened distal portion is less traumatic to the tissue within the body passage. In a preferred embodiment, the lubricous hydrophilic coating is confined to that portion of the catheter liable to be inserted within the endoscope and the body passage. This facilitates initial passage of the catheter to the desired position within the passageway, since the catheter remains in a firmer state until it contacts the body fluid. Since the coating is quite slippery, its absence from the proximal end of the catheter allows the medical professional to retain a firm grip on the catheter as it is manipulated to the desired position. The lubricous hydrophilic coating may optionally also be applied within the spring wire guide lumen and other lumens provided for the insertion of instruments.
Preferably, catheters formed according to the invention are extruded, utilizing a blend of polymers comprised of nylon, especially nylon 11, and an ester linked polyether-polyamide copolymer (PEBA). In the case of biliary catheters, catheters having two or more lumens, one of which is of sufficient diameter to allow passage of a guide wire and to allow passage of another device and the other for a dye or other injectable fluid and having an external diameter of between about 1.8 mm and about 3.8 mm can be formed by an extrusion process. These catheters, when coated with the lubricous hydrophilic coatings of the type herein referred, are extremely supple and offer a kink resistance not obtainable with prior art catheters formed of Teflon(copyright). When formed from the resin blends of the present invention, the catheter material does not exhibit the tendency to bunch up on the wire guide as the catheter is pushed through the passageway. The catheters have good xe2x80x9ctorqueabilityxe2x80x9d, that is to say, the tip follows the proximal end without undue twisting when the medical professional rotates the catheter during placement.
Preferably, the catheter has a central section substantially equivalent in length to the length of the accessory channel of a standard video duodenoscope, a distal section substantially equal in length to the portion of the body passage to be negotiated and a proximal section of a length sufficient to allow for manual manipulation when the distal section is in an extreme position within the body passage. At least the distal section but not the proximal section is coated with a hydrophilic coating which provides lubricity within the passage.
By providing exit ports in the distal tip of the catheter and orienting the ports in a generally axial direction, so that devices or injectable fluids exit distally of the catheter, procedures which involve the advancement of the catheter over the spring wire guide, use of a papillotome or other instrument and injection of contrast medium at successive locations along a relatively confined duct or passageway, such as the biliary duct, are facilitated. By use of at least two lumens having ports facing generally forwardly in the direction of movement of the catheter, removal of the wire guide from the catheter during other procedures can be avoided. Direct visualization devices and other instruments can be passed through one lumen while the spring wire guide remains in place in a second lumen for ongoing repositioning of the catheter as is desired by the user. Catheters according to the invention may be provided with a dilatation balloon or a supporting surface on the distal tip portion for support of a stent. Desirably, additional lumens are reserved for the injection of a tracer dye and aspiration of biliary fluid.